1. Field of the Invention
The present invention relates to a variable-diameter wheel, and more particularly, to a variable-diameter wheel of which a diameter is variable while the wheel is folded or unfolded along a folding pattern.
2. Discussion of Related Art
A variable-diameter wheel of which a diameter is variable may be used in a vehicle which is driven on an uneven and rough road or a robot which performs special purposes such as an explosive detection and a scouting operation.
Generally, in the case of a vehicle wheel, when an obstacle is higher than a wheel shaft, the wheel may be caught by the obstacle and may not pass the obstacle. However, in the case of a vehicle (including a robot) having the variable-diameter wheel, a diameter of the wheel may be increased in this situation, such that the wheel shaft becomes higher than the obstacle, and thus the wheel may go over the obstacle.
The variable-diameter wheel is particularly useful for vehicles or robots having the special purposes such as the explosive detection and the scouting operation. This is because such vehicles or robots should be moved at a place in which obstacles such rocks and stairs are present on a ground surface, as well as a place in which the obstacles are placed at an upper side spaced from the ground, such as a gap between the ground and an upper structure.
When the obstacles are placed on the ground, the diameter of the wheel is increased to go over the obstacles. When the obstacles are placed at the upper side spaced from the ground, the diameter of the wheel is reduced to lower a height of the vehicle or the robot, such that the vehicle or the robot passes the obstacles.
In an example of a well-known variable-diameter wheel, the variable-diameter wheel includes one hub having a predetermined diameter and an expanding piece which is movable in a radial direction of the hub, and has a mechanical mechanism in which a diameter of the wheel is changed according to radial movement of the expanding piece.
However, in the case of the vehicles or robots having the special purposes such as the explosive detection and the scouting operation, considering that a size thereof is gradually reduced to be movable through a narrow space, and a weight thereof is also reduced to increase an operation time on a single charge, a new structure of the variable-diameter wheel in which a diameter thereof is variable with a simple structure, while a weight thereof is reduced, is required.
Meanwhile, a stent using an origami pattern is known as a medical stent. The well-known stent is formed of a tube body having a pattern, so-called “waterbomb pattern”, in which a unit cell is repeated. The tube body may be folded or unfolded along the pattern, and thus a diameter thereof may be variable.